ARRMA Mojave EXB
ARRMA Mojave EXB
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It’s not often that a RC company can be defined by a single platform from their product line, but for ARRMA, I feel that the 1/7 scale Mojave desert-racing truck might just be that one which showcases the best of their engineering and design talents.
I don’t expect this to be universally accepted, but you’d be hard pressed to come up with a better suggestion for the “best all-around” ARRMA platform, and no, it’s not the Kraton. Maybe the Talion as a close second? |
The Mojave is a 1/7 scale desert-racing truck which is known for its ability to tolerate an inordinate amount of bashing abuse all while maintaining a high level of precise handling composure. Unlike the Losi Super Baja Rey or Traxxas UDR, the Mojave is built as a large Short-Course Truck ( SCT ) platform featuring a fully independent suspension and internal drivetrain setup similar to what is found on a 1/8 scale racing buggy.
What it gives up in scale details to the aforementioned trucks, it more than compensates for with impressive performance. Much of this is due to the independent rear suspension, compared to that of the UDR's and Super Baja Rey's which feature solid rear axles. For all intents and purposes, they are a different class of RC platform.
Continuing on, three oil-filled differentials move power throughout the four-wheel drive chassis with front and rear sway bars to maintain control in the corners. Coil-over shocks handle the bumps and jumps with a pillow-ball front knuckle steering design to keep the truck pointed in the right direction.
Underneath the simple lexan body are a series of chassis braces and a large battery holder to accommodate dual 3s or a single 6s battery pack. It’s a very straightforward and open layout which will seem familiar to any driver with buggy or SCT experience.
What it gives up in scale details to the aforementioned trucks, it more than compensates for with impressive performance. Much of this is due to the independent rear suspension, compared to that of the UDR's and Super Baja Rey's which feature solid rear axles. For all intents and purposes, they are a different class of RC platform.
Continuing on, three oil-filled differentials move power throughout the four-wheel drive chassis with front and rear sway bars to maintain control in the corners. Coil-over shocks handle the bumps and jumps with a pillow-ball front knuckle steering design to keep the truck pointed in the right direction.
Underneath the simple lexan body are a series of chassis braces and a large battery holder to accommodate dual 3s or a single 6s battery pack. It’s a very straightforward and open layout which will seem familiar to any driver with buggy or SCT experience.
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Easy to service and maintain, and somewhat overbuilt, it’s a bit of everything ARRMA has labored to achieve, all rolled up into one platform.
I won’t go as far to say I’m biased towards their products, but my list of nits is surprisingly short for a platform I’ve spent a considerable amount of time working with. At the time of this writing, ARRMA offers only one configuration of the Mojave as a RTR ( ready to run ) version, but when we were placing our order, the EXB ( extreme bash ) version of the Mojave was still available, and we went with that model. Unfortunately, today the Mojave EXB is no longer offered. |
Waiting for test laps with the new JConcepts Landmine tire for the Mojave
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The Mojave EXB version comes without electronics, but it does include a fancy matte and gloss black body and a few of the EXB aluminum upgrades inside. It’s not hard to reason out that Horizon Hobbies prefers to sell the RTR version for the additional monies made on the Spektrum electronics and the simplicity for dealers to stock and sell just one variant of the Mojave with just a choice in red or green body color.
That said, not keeping this EXB roller in their lineup is an oversight in my opinion.
That said, not keeping this EXB roller in their lineup is an oversight in my opinion.
Surprisingly good handling characteristics for such a large and powerful desert truck.
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Spoiler Alerts
Rather than attempting to develop any mystery or intrigue as to if the Mojave is a good RC platform, let’s cut to the chase here and now. Yes, we love this machine. If it had an exhaust pipe, it would spew out brilliant rainbows and clouds of cotton candy; it’s that good. So, if you were waiting for the punch line, there it is. If you don’t have one, open another tab on your computer and get one ordered. Get the RTR; it’s still an outstanding machine. |
Next, a short word on our driving style. Driving really fast in a straight line doesn’t interest us. To do that, we would build a drag car or drag Mojave, but in the automotive sense and not Ru Paul sense. There will be none of that in this review; driving in a straight line (for us) is really, really boring.
There will be no top-speed data, no speed runs, and no goofy setups to facilitate speed runs. ARRMA states that the RTR version can hit 60 mph with the right pinion gear. Neato.
There will be no top-speed data, no speed runs, and no goofy setups to facilitate speed runs. ARRMA states that the RTR version can hit 60 mph with the right pinion gear. Neato.
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Conversely, launching off 20’ dirt ramps and seeing how many flips we can do in the air before slamming into the ground, all while being slack-jawed amazed / disappointed that something broke is slightly less interesting than driving in a straight line.
Truth be told, it’s a lot less interesting than driving in a straight line. If I wanted to see it fly, I’d put wings on the truck and throw it off a building. If I wanted to break it, I would just run it over with a tractor, twice, just to prove I was serious about breaking something on the truck. |
dBoots OEM tires digging deep into this corner.
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We like to be different here and use the steering wheel on the transmitter. I realize this might sound like blasphemy to the bashing crowd, but dialing in the suspension, drivetrain, and chassis details for optimal performance is what we are after.
Yes, we know it’s not bashing, and ARRMA is all about bashing. Well, I’m glad this isn’t a popularity contest, and last time I checked the mail, I failed to see any Valentine’s Day cards or endorsement checks from ARRMA or Horizon Hobbies.
Yes, we know it’s not bashing, and ARRMA is all about bashing. Well, I’m glad this isn’t a popularity contest, and last time I checked the mail, I failed to see any Valentine’s Day cards or endorsement checks from ARRMA or Horizon Hobbies.
Rear bulkhead of the Mojave with aftermarket rear-arm mud / rock guards installed.
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Game Plan
After some discussion about project direction, it was decided that setting up the Mojave somewhat like an SCT for short grass and soft dirt was going to be our game plan. We wanted to lean into the precise handling / racing feel of the truck while driving on slightly more aggressive and looser surface than packed clay. The suspension would be tuned for traction and control, and not for massive jumps or straight-line speed. This suspension adjustment would result in lowered ride-height and lower body mount. Along with this, the pinion gearing would be a bit more conservative. To compliment these changes, the electronics would be selected for lower-end torque versus top-end speed. All in all, it’s a relatively vanilla concept compared to some of the more adventurous approaches to reworking the Mojave, but it’s where our interest lies, and we paid full retail for the truck. |
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Electronics Setup
Knowing that the EXB is a roller ( sans electronics ), it’s good to have a baseline knowledge as to what the RTR version comes with. From ARRMA, the RTR Mojave is outfitted with a Spektrum Firms 150 Smart ESC and Spektrum FIRMA 4074 2050Kv motor (43mm diameter, 80mm length). This combination is quite fast on 6s and scratches the basher’s power-hungry itch, fully capable of launching the Mojave into low-earth orbit off ramps or flying across fields at the listed 60mph. For our Mojave, we installed the Hobbywing Max 6 combo, featuring a beastly 4985 SL – 1650 kV motor and 160-amp ESC. Both the ESC and Motor are significantly larger than the RTR version, providing more torque, cooler running temps, and more awesomeness to harness. |
Hobbywing 1650 kV Max 6 combo installed.
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For my driving style, I prefer the lower kV of the motor because it allows a wider range of pinion choice. I’ve seen people run as low as a 17-tooth pinion and as large as a 28-tooth pinion, with this truck running a 21-tooth pinion. On 6s power, there is more than enough top-end speed to work with as well as excellent low-speed control. The massive amount of torque is easy to smoothly apply in the corners without upsetting the chassis stability. The motor also remains cool with just a simple fan mounted on top.
Selecting the right servo is relatively simple in that the Hobbywing Max 6 has an internal BEC which can easily manage a high-torque servo. From Hobbywing’s website: “Super internal switch-mode BEC with switchable voltage of 6V/7.4V and a cont. /peak current of 6A/25A for easily driving big torque servos and high voltage servos.”
Reading this, I pulled a Savox 1270 TG servo from inventory to handle the steering needs. With specs of Torque @7.4v - 35.0kg/486.1oz-in, it’s more than adequate for the Mojave. Recently, Savox phased this unit out for a new and more powerful 1270 TGP, and the specs look pretty good. When the 1270 dies off, mostly likely I will switch to a direct power unit from NSDRC.
Selecting the right servo is relatively simple in that the Hobbywing Max 6 has an internal BEC which can easily manage a high-torque servo. From Hobbywing’s website: “Super internal switch-mode BEC with switchable voltage of 6V/7.4V and a cont. /peak current of 6A/25A for easily driving big torque servos and high voltage servos.”
Reading this, I pulled a Savox 1270 TG servo from inventory to handle the steering needs. With specs of Torque @7.4v - 35.0kg/486.1oz-in, it’s more than adequate for the Mojave. Recently, Savox phased this unit out for a new and more powerful 1270 TGP, and the specs look pretty good. When the 1270 dies off, mostly likely I will switch to a direct power unit from NSDRC.
SMC Lipo batteries continue to impress.
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Batteries
We have been using SMC Racing batteries for a number of years, and while we test different lipo batteries from time to time, they never perform quite as well as the SMC batteries. An example of this is what we have found when comparing the SMC lipo the Spektrum lipo battery. The Spektrum battery quality seems fine, but they feel sluggish on the test track. Other batteries have been tested, and the results tend to be the same to some degree. For lap times and overall handling performance, we use the 5200 mAh SMC packs. |
Some “budget” batteries are terrible with weak power and much shorter track time than their capacity suggests. Because we use lap times in many of our performance metrics, we decided long ago to stay with the SMC batteries for consistency. SMC lipo batteries are not the most expensive on the market, but they do command a fair market price, and investing in over a dozen 6s batteries was a considerable expense.
Thankfully SMC has helped offset some of the cost of these batteries to support our testing. This is all worth keeping in mind when considering our results. SMC Racing also has an interesting link on their website talking about battery quality and what goes into testing and development of lipo batteries.
Thankfully SMC has helped offset some of the cost of these batteries to support our testing. This is all worth keeping in mind when considering our results. SMC Racing also has an interesting link on their website talking about battery quality and what goes into testing and development of lipo batteries.
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Finishing Touches
Before our first run, we pulled the differentials to drain the factory fluid and refill with new fluid. From the factory, the Mojave is set up as 10k / 100k / 10k. This fluid setup makes the truck easy to handle in the corners, but you’re going to struggle to get all the power to the ground and have slower overall lap times. More often than not the factory differentials are not adequately filled, so checking these in any new ARRMA is just good practice. |
Sweeping wide around this corner.
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After a bit of research, we opted to try our first setting as 50k / 200k / 30k. A few of our bashing friends from Cali said they run a bit heavier, so this seems like the right starting point. This should reduce power unloading the front and also increase speed when exiting the corners. The increased fluid viscosity in the rear will provide just enough traction in the rear without it spinning out in the corners due to over-steer from the rear-end breaking free.
The EXB model also features ARRMA's limited-slip differentials (LSD), and our setup is maximum engagement in the front and center differential, with the rear setup as minimal LSD. Again, this setup is to keep the rear-end planted when exiting the corners. I keep mentioning this detail, and I believe in police work they refer to this as a "clue." I'd love to say I came up with this diff setting for the Mojave, but many drivers have already figured this out. That said, in the event you're late to this party, there you go.
The EXB model also features ARRMA's limited-slip differentials (LSD), and our setup is maximum engagement in the front and center differential, with the rear setup as minimal LSD. Again, this setup is to keep the rear-end planted when exiting the corners. I keep mentioning this detail, and I believe in police work they refer to this as a "clue." I'd love to say I came up with this diff setting for the Mojave, but many drivers have already figured this out. That said, in the event you're late to this party, there you go.
As a late addition to this review, I included a link to a handy video on YouTube explaining the LSD setup in the ARRMA differentials and how it all works. Later on I'll update this section here with a few differential photos.
ARRMA LSD Video: LINK
ARRMA LSD Video: LINK
Scorched RC inner fenders (L).
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What Why to Upgrade
The ARRMA line of RC platforms is a bit unique in that they require very few upgrades, even though there is an endless suite of optional parts. With the Mojave, I’ve followed an approach of only upgrading something if it breaks due to wear and tear or if to be found as a poor design aspect, and not just for looks. That said, there is one “should do” upgrade worth the investment, and that’s the Scorched RC inner fender wells. These are easy to trim and install in the Mojave, and require virtually no change or modification to the truck. They keep most of the grass, rocks, and mud from flipping up into the chassis. At $46.00, they will seem a bit spendy, but I found them to be worth the investment if you’re running the Mojave off road. Other things worth upgrading are the bearings as they wear out ( I use AVID bearings ), and also the sway bar mounts. The OEM version is a weird plastic connection, but you can find better adjustable aluminum mounting links on Amazon. Final comment here; drop the dual battery system and just run a single 6s battery. Nothing less than IC5 connectors and 10 AWG wire, and you'll be set. |
Drivetrain components breakdown due to use, and a good source for higher-quality replacements parts is M2C Racing. They have an impressive suite of upgraded parts for the Mojave and are worth a look, and their customer service is excellent.
Knowing that we would be putting our Mojave through a considerable amount of track time for tire testing, we ordered two sets of their drive shafts, outdrives, input shaft cups, and droop screws. The droop screws were installed right away with the other parts as replacement for the OEM items as they wear out.
Knowing that we would be putting our Mojave through a considerable amount of track time for tire testing, we ordered two sets of their drive shafts, outdrives, input shaft cups, and droop screws. The droop screws were installed right away with the other parts as replacement for the OEM items as they wear out.
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Driving Notes
Heading out a the dirt lot for the first time with the Mojave was an eye-opening experience. Compared to the 1/10 SCT’s in the collection, the Mojave is an absolute animal in comparison. The size and speed are perfectly combined, yet it retains the nimble movement of a SCT. Compared to something like the Traxxas UDR with its solid rear axle, the Mojave quickly shows you that it's in another class. What the UDR provides with its scale realism, the Mojave provides brute power and drivability. |
Playtime in the mud.
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Short, wet grass is no match for the OEM dBoots tires.
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After ripping around the gravel for the better part of an hour, we found a few mud holes to play in, and the Mojave didn’t disappoint. Unfortunately for us, we hadn’t installed the Scorched RC inner fenders yet, and had quite a mess on our hands inside the truck.
Fast forward the next 18 months, and we have well over 200 battery packs through the Mojave. Somewhat surprisingly, the wear and tear has been quite minimal. The first upgrade was switching to AVID bearings as the OEM bearings wore out. We service and maintain our bearings, and it seems that the AVID bearings hold up better and spin a little smoother. |
Next was widening the stance by installing the Kyosho +11mm hubs. This modification helped keep things planted in the corners a bit more without inducing excessive scrub in the steering. One thing to note is that with some of the wheel and tire combos we tested, the outside edges of the tires rub the fender wells. Just FYI on this one if you run the body low.
With the stance wider, we lowered the ride height to further plant the truck on the track and swapped out to stiffer shock springs front and rear. The final piece to that puzzle was stiffening the sway bars to 2.6mm in the front and 2.9mm in the rear. The stiffer sway bars allow for a bit more speed in the corners before the inside tires start to lift.
The factory shock fluid is listed as 80wt, but this felt a bit too stiff with the chassis moving up and down more than desired. By swapping to a stiffer spring with the 60 wt fluid, the suspension felt more plush and quicker to react to small bumps and divots in the field.
With the stance wider, we lowered the ride height to further plant the truck on the track and swapped out to stiffer shock springs front and rear. The final piece to that puzzle was stiffening the sway bars to 2.6mm in the front and 2.9mm in the rear. The stiffer sway bars allow for a bit more speed in the corners before the inside tires start to lift.
The factory shock fluid is listed as 80wt, but this felt a bit too stiff with the chassis moving up and down more than desired. By swapping to a stiffer spring with the 60 wt fluid, the suspension felt more plush and quicker to react to small bumps and divots in the field.
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With more time out on our favorite grass track, the Mojave had significantly improved in it's overall performance. The truck is now highly responsive and can impressively carry a substantial amount of speed in the corners.
That said, coming in too hot will quickly put the Mojave on its roof, but all things considered, it really brings the SCT handling precision to the larger scale. At this point we've settled on the battery packs for testing as well as the suspension setting, diff fluids, and shock fluids. |
Hobbywing 1650 Max 6 power on display.
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Now it's time to put the pencil down here and start working on our tire testing review criteria chapter for this website. There is still a considerable amount of info to share about the test track and data collected, so stay tuned for that section coming soon.
All of this information is to set the stage for our tire reviews on the Mojave. With the truck details and testing criteria laid out, the performance results and commentary about the different tires should be straight-forward and easily to understand.
All of this information is to set the stage for our tire reviews on the Mojave. With the truck details and testing criteria laid out, the performance results and commentary about the different tires should be straight-forward and easily to understand.
Current Build Notes
Additional Manufacturer Details
- MOJAVE 4WD EXB Desert Truck
- ARRMA Part Number: ARA7204
- Motor / ESC: Hobbywing 4985SL-1650KV-Max6 Combo
- Servo: Savox 1270 TG
- Pinion: 21T
- Differential Setup: 50/200/30
- Testing Weight Setup:
- Modifications: AVID bearings, Kyosho +11mm hub extensions, Scorched RC fender wells, Aluminum sway bar mounts, 2.6mm sway bar ( front ), 2.9mm sway bar ( rear ), 70mm 1.42N ( front shock springs), 110mm 0.63N ( rear shock springs )
- Shock Oils: 60wt TLR oil front and rear.
Additional Manufacturer Details
- Chassis: 0.12" (3mm) aluminum plate
- Drivetrain: 4WD
- Front Shock Spring Rate: 1.35N/mm
- Product Height: 10.59" (269 mm)
- Wheel Hex Size: 17mm
- Scale: 1/7
- Product Width: 13.98" (355 mm)
- Ground Clearance: 1.85" (47mm)
- Internal Gear Ratio: 4.3
- Product Length: 28.15" (715 mm)
- Spur Gear: 50T
- Differential: 3 oil-filled metal geared
- Max Battery Dimensions: 6.22 x 1.89 x 2.76" (158 x 48 x 70mm)
- Rear Shock Spring Rate: 0.56N/mm
- Sway Bar: 2.4mm ( factory )
- Gear Pitch: 1.0MOD
- Final Drive Ratio: 9.77 - 17.92
- Wheelbase: 16.54" (420 mm)